Used for lemmas that can be used alternatively. Note that two Lemmas linked via lemma-variant differ in some morphological features. Example: a deponent verb that also has an active variant differs from its lemma variant for the voice feature (active/passive).
Note that LiLa is agnostic for what concerns the importance of the two variants. Both lemma variant have the same status. E.g. "sequor" (a very common deponent verb) has also an active variant "sequo" attested in some lexicographical source (see Georges s.v. "sequo"). Though "sequor" is arguably the most important form, both variant are registered equally in LiLa.
Lemma variant is both symmetric and transitive (if A is variant of B and of C, then B is a variant of C)